This invention relates of a process for the preparation of 3,5-xylenol from 3,5,5-trimethylcyclohexen-2-one (isophorone). 3,5-Xylenol and related xylenol isomers are useful as disinfectants and starting materials for the preparation of resins.
It is known from U.S. Pat. No. 2,369,196 that isophorone can be converted to 3,5-xylenol by heating isophorone at temperatures between 668.degree. and 676.degree. C. The yields of product, however, are relatively low (39%). It is also known to use a variety of solid catalysts to improve the yield. Examples of such catalysts are activated alumina disclosed in U.S. Pat. No. 2,369,197 and a chromium (III) oxide-copper (I) oxide mixture known from British Patent specification No. 1,197,803. A disadvantage of such solid catalysts is that during the conversion reaction a carbon deposit is formed on the catalyst. This leads to a decrease in catalyst activity and necessitates stopping the reaction at intervals in order to regenerate the catalyst.
It has now been found that isophorone can be converted to 3,5-xylenol in good yield using certain homogeneous catalysts.